Higher operating temperature typically has a negative impact on both performance and reliability of semiconductor memory devices, which operate more slowly at higher temperature, and fail more frequently at higher temperatures. In addition, as semiconductor memory devices (referred to as “device” or “memory device” herein) operate at higher speeds or frequencies, they tend to consume more power. The increase in consumption of power can cause operating temperature to further increase, thus additionally affecting performance and reliability.
According to one approach, a heat spreader or heat sink can be used to mitigate the rise in device operating temperatures. The heat spreader is typically mounted directly on the top surface of a device, or devices. The heat spreader provides a conductive path to a larger radiating surface area. The larger radiating surface area makes air cooling more effective since there is a larger surface area for the heat to dissipate from into the air.
The method of applying a heat spreader to the surface of the device has the benefit of being very easy to install. Typically, heat spreaders are applied via an adhesive, or held in place via a clamp onto the top surface of the device. In addition, for a relatively low added cost, heat spreaders prove to be an effective method of improving the thermal performance of a device.
The drawback of applying a heat spreader to the surface of the device is that improvements in the thermal path are made only to the heat paths through the top surface of the device package. Thermal paths through the package leadframe/substrate are not improved. The package leadframe/substrate thermal path can be equally critical to the device thermal performance as the top surface path. Therefore, any improvements to the package leadframe/substrate thermal path can significantly improve thermal performance.